Humans, and other animals, commonly suffer from diaphyseal fractures, i.e., breaks of long bones such as the femur, tibia or humerus. Treating these fractures often requires surgery to artificially provide support normally provided by an unbroken bone.
In order to provide the needed support, metal plates are commonly placed along the exterior of a fractured bone and attached by various means, such as screws which connect with the bone cortical tissue. Unfortunately, while plates may provide good support, their implantation requires a relatively invasive surgical procedure which may be detrimental to the patient.
Other approaches include interlocking nail and screw combinations. These methods comprise placing a metal nail within the fractured bone medullary canal and locking it in place with transverse pins or screws which also connect with bone cortical tissue. This approach generally requires a shorter and less invasive surgical procedure. Unfortunately, known interlocking nail/screw combinations do not provide the same level of support as plates. In particular, interlocking nail/screw combinations are less resistant to torsional and bending forces. Clinically, this results in much slower healing times because the (at least) two portions of bone on opposite sides of the fracture are not maintained in a fixed position relative to one another, slowing tissue regeneration.
In addition, the insertion of the transverse screws or pins through the cortical tissue and the nail may be time-consuming and difficult because a surgeon cannot see the nail, or nail hole, because the nail is inside the medullary canal. Thus, it is often necessary for surgeons to rely on radiological guiding to accurately drill through cortical tissue and insert the screws or pins into the nail, exposing themselves and the patients to significant amounts of x-ray radiation during surgery.
Thus, new approaches are needed to treat long bone fractures in ways which combine relatively simple, minimally-invasive, surgical procedures with strong, stable, support means. Also, new approaches are needed to reduce or eliminate exposure to radiation during surgery.